Complete NCERT Solution Class 5 EVS Chapter 7: “Energy — How Things Work”
Complete NCERT Class 5 EVS Chapter 7: “Energy — How Things Work” – All Question Answers included — from “I Observe/I Wonder,” “Think,” “Write,” “Discuss,” “Let’s Reflect,” and all Do You Know?-based conceptual questions. Questions are in the same order as in the NCERT textbook, and answers follow immediately below each question for easy student reading.
Chapter 7 – Energy: How Things Work
Complete NCERT Question–Answer Set (with all textbook sections)
What is Energy?
I Observe / I Wonder
| I Observe | I Wonder |
|---|---|
| The food is getting cooked. | How is it being cooked? |
| The fan is moving. | What makes it move? |
| The bulb is glowing. | What makes it glow? |
| The mixer is making a sound. | What makes it run? |
Answer:
All these actions happen because of energy — which makes things move, glow, produce sound, or change temperature.
From your observation write down at least three things that you have noticed:
Moving: Fan, car, running water
Providing light: Bulb, Sun, lamp
Making a sound: Bell, radio, drum
Making things cool: Refrigerator, air conditioner
Making things hot: Stove, iron, Sunlight
Answer:
All these actions use energy in different forms — movement, heat, sound, and light energy.
Discuss
Q: What makes these things move, shine, make a sound or get warm and cold?
Answer:
All these actions happen due to energy. Energy is what makes things move, light up, produce sound, and change temperature.
Do You Know?
The Flying Snake living in Indian forests can glide through the air by flattening its body.
Explanation:
Even animals use energy from food to move and perform amazing actions like flying or gliding.
Activity 1 – Balloon Experiment
Q: What happens when you release the balloon?
Answer:
When air rushes out of the balloon, it pushes the balloon forward. This shows that moving air has energy and can cause motion.
Think
Q: What would you change in the activity to make the toy move faster or slower?
Answer:
To make it move faster, fill the balloon with more air.
To make it slower, fill it with less air.
Activity 2 – Rubber Band Sound
Q: What happens when you pluck the rubber bands?
Answer:
The rubber bands vibrate and produce sound. This is an example of sound energy.
Think
Q: What happens if you use thinner or thicker rubber bands? Do they sound different?
Answer:
Yes.
- Thinner rubber bands produce high-pitched sounds.
- Thicker rubber bands make low-pitched sounds.
Do You Know?
The Bhadla Solar Park in Rajasthan is one of the world’s largest solar power plants.
Explanation:
This park uses sunlight to generate electricity, showing how powerful solar energy can be.
Activity 3 – Sun-powered Water Warmer
Q: What happens to the water in sunlight and in shade?
Answer:
The cup kept in sunlight becomes warm, while the one in shade remains cool.
This shows that sunlight gives us heat energy.
Do You Know?
In cold regions like Himachal Pradesh, people keep cattle on the ground floor so that the heat from animals keeps upper rooms warm — a smart use of natural energy.
Sources of Energy
Discussion by Teacher
Q: How do you feel when you are hungry?
Answer:
We feel tired and weak because our body doesn’t have enough energy. After eating food, we feel active again because food gives us energy.
Do You Know?
Our brain uses energy even when we are sitting, sleeping, or thinking.
Explanation:
Energy is always needed, even for body functions that we don’t see.
Think
Q: From where do animals get their energy?
Answer:
Animals get energy from food, just like humans.
Do You Know?
Cochin International Airport in Kerala is the first airport in the world completely powered by solar energy.
Explanation:
It uses sunlight to generate all the electricity it needs.
Energy from Fuel
Think
Q: What do cars and scooters need to keep running?
Answer:
Cars and scooters need fuel like petrol or diesel to run. Fuel provides them with energy.
Write
Q: How is food cooked in your house?
Answer:
Food in our house is cooked using LPG gas (cooking gas). In some places, people still use wood or coal.
Discuss
1. What kind of fuel do you use at home for cooking?
Answer: We use LPG gas.
2 What are the problems with using too much wood or coal?
Answer:
- It creates smoke and pollution.
- It leads to cutting of trees and deforestation.
- It affects human health and air quality.
Activity 4 – Understanding How Fuel Works
Q: Which diya burns longer? Why?
Answer:
The diya with oil burns longer because oil acts as a fuel.
Q: What is acting as a fuel here?
Answer:
Oil is the fuel.
Do You Know?
Traditional Indian houses with thick walls and small windows stay cool in summer and warm in winter — a natural energy-saving design.
Electricity
Activity 5 – Devices Using Electricity
| S.No | Device | What It Does | Type of Energy |
|---|---|---|---|
| 1 | Fan | Blows air | Movement |
| 2 | Bulb | Gives light | Light |
| 3 | Refrigerator | Keeps food cold | Cooling |
| 4 | Iron | Presses clothes | Heat |
| 5 | Television | Shows pictures and sound | Light & Sound |
Think
Q: What would your day be like if there was no electricity?
Answer:
Without electricity, we could not use fans, lights, refrigerators, or devices like TV or computers. Our daily life would become difficult and uncomfortable.
Do You Know?
Using LED bulbs instead of ordinary bulbs saves electricity — this is called energy efficiency.
Safe Use of Electricity
Safety Rules:
- Don’t touch wires or sockets.
- Don’t insert objects into plug points.
- Stay away from broken wires or poles.
- Don’t play near transformers.
- Always tell an adult if something looks unsafe.
Answer:
Following these rules prevents electric shocks and accidents.
Do You Know?
In hilly areas, watermills (gharaats) use flowing water to grind grains — a smart use of natural energy.
Generating Energy from Sun, Wind, and Water
Think
Q: Which cloth will dry first—one in the Sun or one in the shade? Why?
Answer:
The cloth in the Sun will dry first because sunlight provides heat energy.
Activity 6 – Pinwheel
Q: What happens to your pinwheel?
Answer:
The pinwheel spins when air moves. This shows that wind has energy that causes motion.
Activity 7 – Sunlight in Focus
Q: What happens to the paper when you focus sunlight with a magnifying glass?
Answer:
The paper burns because sunlight produces heat energy when concentrated.
Activity 8 – Water Wheel
Q: Does the water make the wheel move?
Answer:
Yes. Flowing water makes the wheel move. This shows that moving water has energy.
Do You Know?
Ancient ships used wind energy in sails to travel across the seas — early examples of renewable energy use.
Do You Know?
The Sun is the main source of energy for all life on Earth.
Think
Q: Have you seen papads or clothes drying in sunlight?
Answer:
Yes, sunlight dries papads and clothes because it provides heat energy.
Write
Q: Can you think of more examples where we use the Sun, wind, or flowing water?
Answer:
- Sun: Solar cookers, drying grains, solar panels
- Wind: Windmills, sailing boats, flying kites
- Water: Watermills, hydroelectric dams
Do You Know?
Clean energy from the Sun, wind, and water does not cause pollution.
Energy All Around Us
| Activity | Source of Energy |
|---|---|
| A child carrying a school bag | Food |
| A car moving | Fuel |
| A fan spinning | Electricity |
| Clothes drying | Sunlight |
| A windmill turning | Wind |
Do You Know?
Batteries store energy for future use — like our body stores food energy.
Activity 9 – Energy Flow Game
Example Answers:
- Sun → Heat → Dries clothes
- Wind → Movement → Turns turbine
- Food → Movement → Helps us run
- Water → Movement → Turns water wheel
- Electricity → Light → Lights up rooms
Answer:
This game shows that energy flows from source → type → use.
Let’s Reflect
1. What will happen if there is no electricity in your house for a day?
Answer: We won’t be able to use lights, fans, or other appliances. Life will become difficult and uncomfortable.
2. Why is it better to use solar or wind energy instead of coal?
Answer: Solar and wind energy are clean and renewable, while coal causes pollution and smoke.
3. Give two examples where you have seen energy being stored.
Answer:
- In batteries (torches or toys)
- In our body (food energy stored as fat)
4. What is the one thing you can do at home to save energy?
Answer: Turn off lights and fans when not in use.
5. Find out how many kilometres a vehicle travels per litre of petrol or diesel.
Answer (Example):
- Car: 15 km/litre
- Bike: 50 km/litre
(Bikes are more fuel-efficient.)
6. List any three objects that use energy and mention their source.
Answer:
- Fan → Electricity
- Stove → Gas
- Car → Fuel
Create and Share
(a) Draw or plan a ‘Clean Energy Home’ using solar panels, open windows for light, and plants for cooling.
(b) Keep ‘My Energy Diary’ — note how many times you used electricity, fuel, and sunlight in a day.
Summary Concept:
Energy is all around us — from the food we eat, the fuel we burn, to the sunlight that warms and lights our world.
We must use energy wisely and choose clean sources to protect our planet.
Other Important Notes Related to This Chapter
NCERT Question Answer Solution Class 5 chapter 7 – Energy: How Things Work
CBSE Summary Notes Chapter 7 – Energy: How Things Work
Extra Questions Chapter 7 – Energy: How Things Work
Practice Worksheet Chapter 7 – Energy: How Things Work